Although chemical pesticides are valuable in the control of pests, their use poses many problems. They tend to harm non-target organisms such as humans, domestic animals, beneficial insects, and wildlife. In addition, their residues tend to remain on the crop and may accumulate in the soil, water, or air. Another concern is the development of resistance to pesticides by the targeted organisms. Due to the serious environmental problems associated with chemical pesticides, the demand for safer pesticides and alternate pest control strategies is increasing.
It has become widely known in the art that certain live biological control agents (bacteria, phage, bacteriophages) have some use in pest control. The success of these biological control agents depends on understanding the biology of these agents and of the target pest. Several limitations are associated with the use of these biological agents according to conventional techniques. One of the limitations is that some of the biologic control agents are opportunistic pathogens against humans or animals. Another constraint is the competition between the native organisms (beneficial or pathogens) in the ecosystem and the control agents. In many cases, the control agent is not able to compete in the environment and the efficacy of the treatment is questionable.
U.S. Pat. No. 5,767,090 describes the use of rhamnolipids against the transitional zoosporic stage of zoosporic fungi. Although rhamnolipids are very effective against this motile stage of the pathogenic fungi, successful treatment in commercial crops production depends greatly on application time and repetitive applications are sometimes necessary to achieve the desired control. During wet conditions foliar application may be impractical and repetitive applications significantly increases production cost.